Key term
Eduqas A-Level Physics A420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Circular Motion
Vibrations
Topic overviewDefining simple harmonic motionFrequency, period, amplitude and phaseThe displacement equation for simple harmonic motionVelocity in simple harmonic motionDisplacement and velocity graphsThe mass-spring oscillatorThe simple pendulumEnergy in simple harmonic motionFree oscillation and dampingForced oscillation and resonance
Kinetic Theory
Thermal Physics
Conduction of Electricity
Resistance
Topic overviewPotential difference and the voltResistance, Ohm's law and the ohmI–V characteristics of a metal wire and a filament lampElectrical power and energy transferThe microscopic origin of resistanceResistivity and the equation R = ρl/AResistance and temperatureSuperconductivity and the transition temperatureHigh temperature superconductors and their uses
D.C. Circuits
Capacitance
Solids Under Stress
Electrostatic and Gravitational Fields of Force
Topic overviewElectric field strength and Coulomb's lawGravitational field strength and Newton's law of gravitationField lines and equipotential surfacesElectric potential and potential energyGravitational potential and potential energyResultant fields and potentials from several sourcesComparing electric and gravitational fields
Using Radiation to Investigate Stars
Orbits and the Wider Universe
Topic overviewKepler's laws of planetary motionNewton's law of gravitation applied to planets and satellitesDeriving Kepler's third law for a circular orbitUsing orbital data to find the mass of the central objectGalactic rotation curves and dark matterThe centre of mass of a two-body systemThe Doppler shift of spectral lines and radial velocityMasses in a double system from radial velocity dataHubble's law, the age of the universe and its fate
The Nature of Waves
Wave Properties
Topic overviewDiffraction at slits and obstaclesWavelength, slit width and the spread of the beamThe principle of superpositionCoherence and the conditions for interferencePath difference and the interference conditionsYoung's double slit experimentThe historical importance of Young's experimentThe diffraction gratingComparing the grating with the double slitStationary waves
Refraction of Light
Photons
Topic overviewPhotons and the quantum of lightDemonstrating the photoelectric effectThe vacuum photocell and stopping potentialEinstein's equation and the energy graphThe electromagnetic spectrum and photon energiesLine emission and line absorption spectraAtomic energy levelsIonisation energy from an energy level diagramElectron diffraction and the de Broglie relationship
Lasers
Nuclear Decay
Topic overviewSpontaneous decay and the nature of α, β and γ radiationNuclear transformation equations and nuclide notationDistinguishing α, β and γ by ionisation, penetration and rangeBackground radiation and gamma intensity with distanceActivity, the becquerel and the decay constantThe exponential decay law and half-life
Particles and Nuclear Structure
Topic overviewThe Rutherford alpha particle scattering experimentCoulomb repulsion in the plum pudding and Rutherford modelsQuarks and leptons: the first generationAntiparticles, annihilation and their symbolsHadrons: baryons, antibaryons and mesonsQuark composition of the proton, neutron and pionsThe four fundamental interactionsConservation laws in particle reactions
Nuclear Energy
Magnetic Fields
Topic overviewThe motor effect and Fleming's left-hand ruleF = BIl sinθ and measuring magnetic flux densityThe force on a moving charge, F = Bqv sinθThe Hall effect and the Hall probeMagnetic fields due to a straight wire and a solenoidForces between current-carrying conductorsCharged particle beams and accelerators
Electromagnetic Induction
Option A: Alternating CurrentsOption A
Topic overviewElectromagnetic induction in a rotating coilFrequency, period, peak and rms valuesMean power dissipated in a resistorUsing an oscilloscope to measure voltage and frequencyInductors in a.c. circuits and inductive reactanceCapacitors in a.c. circuits and capacitive reactancePhasors, phase angle and impedanceResonance in the series RCL circuit and the Q factor
Option B: Medical PhysicsOption B
Topic overviewThe nature and properties of X-raysX-ray production and controlling the beamAttenuation of X-rays and half-value thicknessX-ray imaging, fluoroscopy and radiographyComputed tomography scanningUltrasound generation and acoustic impedanceUltrasound scanning and the Doppler techniqueMagnetic resonance and MRIRadiation effects on living matter and dosimetryRadionuclide tracers, the gamma camera and PET
Option C: The Physics of SportsOption C
Topic overviewCentre of gravity, stability and topplingMoments in muscle systems and other sporting contextsImpulse and Newton's second law in sportThe coefficient of restitutionMoment of inertiaAngular acceleration, torque and angular momentumConservation of angular momentum and rotational energyProjectiles, Bernoulli's equation and drag
Option D: Energy and the EnvironmentOption D
Mathematical Requirements (Appendix C)
Topic overviewUnits, prefixes and standard formSignificant figures and arithmetic meansUncertainty and how uncertainties combineRatios, proportionality and order of magnitude estimatesRearranging and solving physics equationsLogarithms, exponentials and decayResolving vectors, Pythagoras and trigonometryRadians, small angles, areas and volumesStraight-line graphs, gradients and interceptsTangents, areas under curves and logarithmic plots
Energy Concepts
Power, dissipative forces and efficiency
- 3 things to know
- Component 1
Overview
Equation P = Fv, defining every symbol and its unit, dissipative force and equation for efficiency as a percentage.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State the equation P = Fv, defining every symbol and its unit, and explain how it follows from P = W/t.
Key term
Explain why a car has a maximum speed on a level road even though the engine power is constant.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define power.
Model answer
Power is the rate at which energy is transferred, or equivalently the rate at which work is done.
- 2
State the equation linking power, work and time, defining every symbol and its unit.
Model answer
The equation is P = W/t, where P is the power in W, W is the work done or energy transferred in J and t is the time taken in s.
- 3
Define the watt.
Model answer
One watt is a rate of energy transfer of one joule per second.
- 4
State the equation P = Fv, defining every symbol and its unit, and explain how it follows from P = W/t.
Model answer
In P = Fv, P is the power in W, F is the force in N and v is the steady speed in m s⁻¹. Since W = Fx, dividing by t gives P = F(x/t), and x/t is the speed.
- 5
A crane raises a 500 kg load through 12.0 m in 20.0 s. Calculate the useful power output. Take g as 9.81 m s⁻².
Model answer
The work done is 500 × 9.81 × 12.0 = 5.89 × 10⁴ J, so the power is 58860 ÷ 20.0 = 2.94 × 10³ W. Multiplying 2943 W by 20.0 s returns 5.89 × 10⁴ J.
- 6
A car engine delivers 30.0 kW while the car travels at a steady 20.0 m s⁻¹. Calculate the total resistive force.
Model answer
At constant speed the driving force equals the resistance, so F = 30000 ÷ 20.0 = 1.50 × 10³ N. Multiplying 1500 N by 20.0 m s⁻¹ returns 30.0 kW.
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